You might want to look at some of the 12v heavy duty air pumps sold by
most auto/truck places to inflate tires. I'd consider one with at least
an 8 hour duty cycle which usually means they have a built in cooling
fan. A built in thermal cut out would be a good feature as well.
Obviously the pump needs to be able to reach 120+ psi. I'd be reluctant
to use an electric pump with under an hour's duty cycle as it might
overheat rapidly. Whatever you put in, it would be wise to test it
under worst case conditions to be sure it doesn't overheat and start a
fire. The mounting location should avoid engine heat and provide a
cooling air stream.
> I dont know what the fuss about electric compressors is.
> My car has a vacuum compressor and it does a great job even around town
> running errands. The only problem I have with my car is that I will
> sometimes not use it for several weeks and the air leaks down. Then it
> takes forever for the vacuum compressor to bring it back up. An electric
> compressor would then be ale to pump it up before I go out, but I intend to
> keep that noisy thing in the garage, not in the car!
> Ny vacuum compressor looks just like the one that used to be available from
> J.C.Whitney as an air horn pump for about $30
> "I dont fear death, I just dont want to be there
> when it happens."
> Woody Allan